The present invention relates to an electronic device including a switch-type electronic device such as a push switch adapted to be mounted on a printed circuit board to be disposed in various kinds of electronic apparatuses.
There are known various kinds of switch-type electronic devices such as a push switch mounted on a printed circuit board of an electronic apparatus (see, Japanese Patent Publication No. 9-120742 A).
As the conventional switch-type electronic device to which the countermeasure for the static electricity is applied, one example will be described by referring to FIGS. 10 to 14.
As shown in FIG. 11, a push switch 101 comprises a box-shaped housing 102 formed with a space 103 an upper side of which is opened. A circular dome-shaped movable contact 104 made of an elastic thin metal plate is disposed on an inner bottom part of the space 103. A central lower face of the movable contact 104 opposes fixed contacts 105a and 105b each of which is made of the thin metal plate and fixed on the housing 102 by insertion molding. A protective film 106 is disposed on an upper part of the movable contact 104, and an operating member 107 made of resin is disposed on the protective film 106. A cover 108 made of metal is attached to the housing 102 so as to cover the operating member 107 from above.
The housing 102 includes engaging projections 109 respectively protruding outward along a lower face 102c of the housing 102 at right and left corners of front and rear side faces 102a and 102b of the housing 102. Further, in the other end sides, lead terminals 105A and 105B are provided that are directed outward the right and left side faces 102d and 102d of the housing 102 from the lower face 102c. 
The operating member 107 includes a pressed part 107a and an elastic actuator 107b. The pressed part 107a extends from a front side face 102a of the housing 102 through an opening 111 formed in the front side face 102a. 
The cover 108 is located on an upper face of the housing 102. The cover 108 includes an upper plate 108a having an inclined piece obliquely extended from a center part thereof toward the inside of the space 103. A pair of legs 108a are extended downward from a front edge of the upper plate 108a along the front side face 102a of the housing 102. A pair of legs 108b are extended downward from a rear edge of the upper plate 108a along a rear side face 102b. At a lower end of each of the legs 108b, an engagement piece 108c is formed so as to oppose a lower face of an associated one of the engagement projections 109. The engagement pieces 108c are bent and caulked so that the cover 108 is retained on the housing 102.
The pair of right and left legs 108b provided in the front side face 102a of the housing 102 are separated from each other sufficiently so that at least the operating member 107b of the operating member 107 can be translated therebetween.
In the push switch 101 mounted on the printed circuit board 115 in such a way, under a state that the operating member 107 is arranged at a position shown by a dashed chain line in FIG. 11, when a front end of the pressed part 107a is horizontally pressed rearward, the operating member 107 horizontally moves on the protecting film 106 along the upper face of the housing 102 and the end of the operating member 107b is directed downward by the inclined piece 110 to apply a push down force to the movable contact 104 located at a lower part.
When the push down force exceeds a prescribed level, as shown by a solid line of FIG. 11, the lower face of the central part of the movable contact 104 moves downward and comes into contact with the fixed contacts 105a and 105b to obtain a conductive state (turn-on state) in which the lead terminals 105A and 105B are short-circuited through the movable contact 104. As an amount of pushing operation of the operating member 107, when the rear face of the pressed part 107a abuts against the front side face 102a of the housing 102, a further pushing operation is regulated.
When the operating force of the pressed part 107a is released, the movable contact 104 is self-restored to an original attitude to push up the operating member 107b and the end of the operating member 107b is guided by the inclined piece 110, so that the operating member 107 is pushed back forward to the position shown by the dashed chain line in FIG. 11 to return to an original non-conductive state (turn-off state).
However, the above-described conventional push switch has a structure that the operating member 107 is continued to be pressed from outside the front side face 102a of the housing 102 until the operating member 107 abuts against the front side face 102a of the housing 102. The forces acting on the respective members during in the above pushing operation will be described with reference to FIG. 13. When the operating member 107 is pushed with a force (a pressing force) P, a pushing up force gradually acts on the cover 108 as the pushing operation proceeds. This force acts on the legs 108b as a force (a reaction force) f for pushing the legs 108b outward. In such a case, there is a probability that the legs 108b and the cover 108 would be deformed to damage a function of the switch.
In these days, downsizing of such a push switch is strongly demanded. The width of each side face of the housing 112 is required to be no greater than 3 mm, and the thickness of the cover 108 is required to be no greater than 0.2 mm. In such a size, the above-described deformation becomes remarkable.
As a countermeasure for preventing the deformation, the thickness or the size of the cover 108 or the width of the leg 108b may be increased to ensure the strength of parts. However, contrary to the above-described demand, the size of the push switch is increased.